[X86] Add VPSLLI/VPSRLI ((X >>u C1) << C2) SimplifyDemandedBits combine

Repeat of the generic SimplifyDemandedBits shift combine

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350399 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed